alpha-chymotrypsin and Leukemia--Lymphoid

The acute lymphoblastic leukemia- (ALL) associated membrane antigen is a single glycosylated polypeptide of approximate m.w. of 100,000 (gp100), containing no intrachain disulfide linkages. Approximately 50% of gp100 will bind to lentil lectin, whereas 100% will bind to the lectin from Ricinus communis. Both lentil-binding and lentil nonbinding forms of the antigen appear to be identical by 2-dimensional isoelectric focusing/SDS polyacrylamide gel electrophoresis and peptide mapping. Carbohydrate, although contributing approximately 20 to 25% of the m.w., appears not to be involved in the antigenic site of the ALL antigen as judged by precipitation of a molecule after tunicamycin treatment of cells or glycosidase digestion. Charge shift electrophoresis and labeling with the lipophilic nitrene reagent hexanoyl diiodo-N-(4-azido-2-nitrophenyl)-tyramine suggests that the cALL antigen is probably not an integral membrane protein; however, it remains tightly bound to the plasma membrane after subcellular fractionation. A glycoprotein of the same m.w. has been detected by immunoprecipitation on bone marrow cells of nonleukemic patients. serologic studies indicate that the cALL-associated antigen is found on the terminal transferase-positive lymphoid cells, and it therefore seems likely that the gp100 molecule is a normal gene products of lymphocyte precursors.

Topics: Animals; Antigens, Surface; Cell Differentiation; Chemical Phenomena; Chemistry; Chymotrypsin; Electrophoresis, Polyacrylamide Gel; Epitopes; Glycoproteins; Isoelectric Focusing; Lectins; Leukemia, Lymphoid; Lymphocytes; Molecular Weight; Peptides; Rabbits; Trypsin

Histones F2al extracted from normal and neoplastic cells possess similar amino acid compositions. Tryptic and chymotryptic peptides of the F2al histones have identical chromato-electrophoretic R(F) values. It is concluded that histones F2al from various sources have similar overall structures. The observed differences in the ratios of in-N-monomethyl- and di-in-N-methyl-lysine in the histones from normal and neoplastic cells may be of significance with respect to gene regulation.

Topics: Amino Acids; Animals; Carcinoma, Hepatocellular; Cattle; Cell Line; Chromatography; Chromatography, Gel; Chymotrypsin; Cyanides; Electrophoresis, Disc; Histones; Humans; Leukemia, Lymphoid; Liver Neoplasms; Lymphoma, Non-Hodgkin; Neoplasms, Experimental; Thymus Gland; Trypsin